1. Field of the Invention
The subject invention relates to fiber spin finishes containing fiber lubricants which produce low residue levels. More particularly, the invention relates to the use of polyoxyalkylene polyether diols based upon 2,2-dialkyl-1,3-propanediols as spin finish lubricant additives.
2. Description of the Related Art
Fiber finishing compositions are a necessary part of modern, high speed synthetic fiber manufacture. Virtually all operations performed on the fibers following their being spun from the melt require the presence of suitable fiber finishes to prevent snarling and breaking, thus enabling higher fiber throughput. Generally speaking, a quality fiber finish must provide several, often conflicting qualities. For example, the fiber finish must qualify both the interaction between the fiber and the machinery on which it is processed, and also the interactions among the fiber filaments themselves. This property is usually termed "lubricity" although in reality the change in the interactions caused by the fiber lubricant may sometimes result in a desirable increase in friction as well as the decrease in friction ordinarily associated with the term "lubricant."
In addition to its "lubricant" qualities, the fiber finish composition must control static electricity generated during fiber processing. Generally, ionic organic compounds such as synthetic phosphate and sulfonate detergents are useful as antistats and are added to the fiber finish composition for this purpose.
The fiber finishes are generally applied in the form of an aqueous emulsion by any one of several methods including the use of kiss rolls, sprayers, baths and squeeze rollers, and grooved ceramic guides and metering pumps. To maintain a stable emulsion of the lubricant and antistat components, surfactants such as fatty alcohol oxyethylates and nonylphenol oxyethylates are generally necessary.
A suitable fiber finish must also be easily removable from the fiber or yarn so as not to interfere with subsequent operations such as dyeing and bleaching. Furthermore, since the finish performs its intended functions only on the outside of the fiber, it should not be easily absorbed into the fiber proper. Penetration of the fiber lubricant into the fiber increases the quantity of lubricant required during the finishing operation and, in addition, may cause undesirable changes in the physical properties of the fibers themselves.
As the fiber throughput associated with modern fiber finishing operations have increased, the demands placed upon the fiber finish, especially the lubricant which comprises a major portion of the finish, have increased as well. In drawing and twisting operations, for example, the fiber is drawn across a heater plate, hot draw roll or heating pin in order to raise the temperature of the fiber to the plastic deformation stage. The fibers then undergo stretching, twisting, tangling, or a combination of these operations. The cooled, stretched fiber generally has a much higher tensile strength than the raw fiber. If the fiber has been twisted or tangled in addition to being stretched, it retains these modifications, thus imparting improved feel, fabric cover, recovery from deformation and other properties felt desirable by the textile industry. The fibers may also be textured by processes such as stuffer-tube crimping and edge crimping. These processes also require the fibers to be heated to the same relatively high temperatures as for drawing and twisting, generally in the neighborhood of 190.degree. C. or higher.
As the fiber throughput increases, the temperature of the heating elements must be increased as well in order for the faster moving fibers to be heated to the requisite processing temperatures. Fiber processing machinery is capable of running at speeds in excess of 1000 m/min. At these high speeds, however, the primary heater plate temperature must be maintained at temperatures of 250.degree. C. or higher to enable sufficient heat transfer to the fast moving fibers. At these high temperatures, prior art lubricants resinify causing a rough resinous coating to cover the heater plate. This buildup of resinous coating on the heater plate not only causes decreased thermal transfer from the plate to the fiber but, more importantly, is a primary cause of broken filaments. The need for a fiber lubricant which will not build up resinous deposits at high temperatures has heretofore limited operating speeds to 700 to 800 m/min. for this reason. In addition to causing broken filaments, the resinous heater plate deposits may adhere to the fibers, causing additional problems such as uneven dyeing in subsequent operations owing to the greater difficulty in removing the resinous by-products as opposed to the unaltered lubricants themselves.
Due to the loss of production time necessitated by cleaning operations or, in some cases equipment replacement, caused by buildup of fiber finish residue, low residue is important even for lower speed operations, or operations with heavy denier fibers. Although the buildup of residue is much slower under the lower temperature conditions of slower fiber finishing, eventually a residue level is reached which requires cleaning and replacement operations to be performed. Thus fiber lubricants which yield low residue are important for both low as well as high speed fiber processing.
Prior art lubricants include mineral oils and waxes, fatty acid esters such as butyl stearate, vegetable oils and waxes, neoalcohol esters, silicones, and polyoxyalkylene polyethers. Among the fiber lubricants yielding the least resinous buildup for high speed fiber processing, for example, are the propylene oxide/ethylene oxide block copolymers such as PLURONIC.RTM. L-31 block copolymer surfactant. In pan tests at 210.degree., for example, PLURONIC.RTM. L-31 typically has less than 3 percent by weight unvolatized residue after four hours and less than 1 percent after 24 hours. However, even these relatively small amounts of residue can produce resinous buildup on the heater plates when processing speeds of greater than 700 to 800 m/min. are utilized. Thus, the requirement of a low residue fiber lubricant suitable for high speed fiber processing has not been met in spite of the long-felt need for such a product.